ES2297097T3 - FLAT GASKET RING. - Google Patents

Abstract

The flat sealing ring (1) for a fluid-tight joint between two surfaces pressed against one another comprises a stiffening ring (3) which is located at the inner and/or outer periphery of the elastically deformable main ring (2). The stiffening ring is less flexible than the main ring in the direction perpendicular to plane of the sealing ring. It also has a smaller height than the maximum dimension of the main ring in this direction.

Description

Flat seal ring

The invention relates to a flat seal ring to establish a fluid tight connection between two flanges that close tightly by a clamping force of one against the other, where the ring has an elastic base ring deformable In space the invention relates to a seal ring plane with defined recovery and compression capacity, which in a special design can be used advantageously in the chemical, petrochemical and food industry, when provided with a chemically resistant and / or non-damaging surface layer to health.

Flat gaskets or flat gasket rings that they can be subjected to high loads are used in the technique of apparatus, pumps and pipes to establish watertight joints fluids Flat gasket rings are compressed by a rotating movement around the central axis of the seal ring, such as threaded joints of valve bodies in pipes or pump housings, or by pressure movements perpendicular to the plane of the seal ring, that is, parallel to the axis of the seal ring, for example for flange joints between two sections of pipe. Pressure ensures a close, solid contact between the joint material and the two parts that must be joined together in a fluid tight manner.

PTFE flat joints are known (Pure polytetrafluoroethylene) used primarily in the chemical, petrochemical and food industry because of its Chemical resistance and not be harmful to health. A disadvantage of these joints is that the PTFE material is not elastic and therefore it does not possess any recovery force. These boards of Pure PTFE or any other non-elastic material can therefore be used basically only once. When expressly demands a recovery power or if the fluid tight connection between two pieces should be opened frequently, the joints of this Type should not be used at all. PTFE gaskets only they are allowed to compress in a limited way and have inclination to "flow", so that the moments of tightening of a union threaded or the force with which the tightening originally occurred are reduced after a certain time of service. Therefore in the time course a lack of tightness may occur even if the gasket is only tightened once and then it is not Release again

For document DE 299 09 268 U and for DE 299 09 270 U document known flat seal rings with those who try to solve the disadvantages of the flat joints of Pure PTFE The seal rings are essentially formed of two PTFE layers that in the compression zone form between them a hollow or pocket in which a ring of a sheet of corrugated metal perpendicular to the plane of the ring. Alternatively, in the PTFE hole or in the PTFE pocket is provided an insert of an elastic material. By compressing the gaskets with wavy metal ring inserts metal waves they are crushed under the force of compression. This type of joints guarantees tightening or compression with tightening moments prescribed and a safe sealing effect forever. Together with wavy metal ring inserts are however usable limitedly in plastic threaded joints because In general the joint is very hard for the plastic material. For Threaded plastic joints are more suitable in this case together with an insert of an elastic material, which in the joints known are inserted loose in the PTFE hole. However it has shown that by tightening the threaded joints the insert of elastic material is pressed out of the PTFE gap due to the spin and spider movement to the PTFE gap. Why not safe sealing of the threaded joint can be guaranteed. Too often the insert of compressed elastic material out weld the thread of the threaded joint which further hinders the tightening.

Document DE 198 46 475 A1 describes another flat seal ring in which a base ring of a material Elastic is covered by a PTFE protective sheet. He elastic material and PTFE protection sheet are then joined with each other in such a way that during the compression of this together the elastic material is no longer pressed out. This board has however the disadvantage that it does not guarantee any surface pressure or sealing force over a long period of operation because the clamping forces or the forces of compression are absorbed directly and completely by the ring of elastic material coated with a protective foil (closure main by force). Therefore it is easy to reach a strong board crush. The board is easily too much crushed and remains deformed, so that the board is unsuitable for a new use or the sealing effect is lost after opening and tightening the joint again.

The document US-A-3,775,832 describes a ring of gasket consisting of a ring-shaped sheath of a solid, hard and non-dilatable fluoropolymer with an annular core plane of an elastomeric material provided in this sheath, where the annular sheath also extends along the inner peripheral edge of the elastomeric annular core. Also here you can reach easily to seal the gasket too much and remain deformed, so that the board will be inadequate for a new use or sealing effect will be lost after opening and tighten the gasket again.

In the document US-A-2,859,061 a ring is described of compound joint, which has an annular core compressible of an elastomeric material, around which it is placed a flexible protective cap, annularly, which for example it can be made of PTFE and whose ends marginal form a lip. Since the core sits loose in the socket and there is no firm union between the two components, using these joints in joint sealing threaded it can happen that by the turning movement a displacement between the core and the bush that affects disadvantageously to the sealing effect.

Document DE 297 07 063 refers to a flange gasket with an elastic base body as well as an element stiff reinforcement. The elastic base element of this flange joint It is provided with a polytetrafluoroethylene (PTFE) coating, where the coating covers at least the surfaces of closure and inwardly oriented surfaces of the body base. The base body of this flange gasket is made preferably elastomer and the reinforcing element preferably steel. In flange joints of this type the sealing function is performed only by the elastic base ring coated, which can sometimes be a disadvantage.

The present invention therefore has the mission of prepare an improved flat gasket ring with respect to the state of the technique, especially with respect to the seal ring described in US-A-2,859,061, with the that can be securely sealed both threaded joints and also joints with flanges, which can be used several times and in that the compression can be done under tightening moments default

This mission will be solved by a flat gasket ring according to the invention, of the type described at the beginning, wherein the flat gasket ring has a deformable elastic base ring and at the inner peripheral edge of the base ring and / or at the peripheral edge outside the base ring has a reinforcement ring, where the reinforcement ring has at least perpendicular to the plane of the ring less deformability or greater rigidity than the base ring and where the height of the reinforcement ring perpendicular to the plane of the ring it is less than the greater height of the base ring perpendicular to the plane of the ring and where at least one area of protection is provided on the outer surface of the elastic base ring, at least one layer of protection with the reinforcement ring in PTFE or other material that with respect to its chemical stability against corrosion is similar to PTFE, characterized in that
The reinforcement ring is connected to the base ring by a process of manufacturing by projection or by adhesive.

The base ring of the chord ring with the invention it is composed entirely or at least in the core of a deformable elastic material, where it can be used All suitable elastomer. Preferably rubber is used for this as solid material or as foam material. Elastic material deformable base ring is responsible for the ability to board recovery and equal and lasting support from flat seal ring on the parts that must be joined one with another fluid tight.

Since often the elastic material deformable base ring in the usual applications for this type of flat seal rings does not meet the requirements of chemical stability and / or requirements of not being detrimental to the health, for example when used in the food industry, in a totally advantageous constructive form of the invention the material Elastic base ring is provided, at least by areas, with one or several layers of protection of a suitable material. As a cape of protection is suitable all material known in the sector that present the required chemical stability and / or not being harmful for health along with the ability to seal tightly the fluids. Especially preferred is a layer of PTFE protection. The protective layer is placed on the elastic material at least everywhere where the joint can become in contact with the fluid, whose entrance must protect the flat seal ring in accordance with the invention. Advisable the protection layer extends throughout the upper face of the base ring, from it to above the inner surface of the ring up above the lower face of the base ring. Alternatively, it can also be wrapped all the elastic material of the base ring with the layer of protection. In another constructive way, on the elastic material of the base ring are provided several layers or layers of protection in the form of layers on top of each other, where the layer more outside, the one that will be in contact with the fluid should present the characteristics of the individual layer mentioned above.

The reinforcement ring provided in accordance with the invention has a lower deformability or a greater solidity than the base ring, which is composed of at least the elastic material and preferably of one or several layers of protection placed on he. Preferably, the reinforcement ring is made of a hard plastic, such as polyamide, or metal. Especially suitable is a stainless metal or resistant to corrosion, preferably stainless steel, at the same time the reinforcement ring has, perpendicular to the plane of the ring, that is, parallel to the central axis of the ring, a smaller height or less expansion than the base ring. When placing and compress the flat gasket ring the parts that must join a with another to seal the fluid move towards each other in perpendicular to the plane of the ring, either by the threaded joint or by pressure movement. During the movement of the pieces of towards each other, first the pieces get in touch with the base ring, and when compressed the base ring deforms from elastic way, that is to say it folds over itself. By force Recovery of elastic material ensures that the ring base will also make a fluid-tight contact on the surfaces of the parts to be sealed. Reinforcement ring It fulfills the mission of limiting sealing compression. So soon as both pieces to be joined rest on the ring  of reinforcement the pieces can no longer move towards each other and the deformable elastic base ring is no longer compressed. With this prevents the deformable elastic base ring from crushing too much, in some cases spread laterally by pressure or It is damaged in some way. The deformable elastic base ring responsible for the seal itself is protected against damage and with this can exercise its sealing function in a lasting way and be reused even after multiple openings of the meeting. The reinforcement ring guarantees not only that a very large compression but also a small compression, put which, due to the compression limitation, indicates both the maximum and The minimum compression. The tightening moments remain constant over time.

Especially preferred, the seal ring plane according to the invention has a reinforcement ring that extends or along the inner circumferential edge of the base ring or by the outer circumferential edge of the base ring. With the Compression of the flat seal ring ensures that the base ring deformable elastic, which when compressed becomes flatter and more large, it can be deflected in the opposite direction to the ring of reinforcement. If the reinforcement ring extends over the edge outer peripheral of the base ring, then when compressed, the deformable elastic material can escape in the direction of center of the ring and vice versa. According to the requirements and design of the deformable elastic base ring may be suitable however if two reinforcement rings are provided, one on the peripheral edge inside and one on the outer peripheral edge of the base ring.

Suitably the reinforcement ring is joined solidly or by closing form with the base ring. In a preferred constructive form the reinforcement ring is vulcanized by form closure within the deformable elastic material of the base ring, the reinforcement ring being able to remain totally or alone partially surrounded by elastic material. In the ring of flat gasket according to the invention the connection between the base ring and The reinforcement ring is produced by projection procedures or adhesion adhesions, which are suitable for a joint of this type.

In the flat seal ring according to the invention the reinforcement ring is made of the same material as the protective layer located on the base ring and is constructed One piece with her. The material is a chemically material resistant, especially PTFE, or PTFE-like materials. In the flat seal ring according to the invention the ring of reinforcement has the same advantageous chemical resistance against the corrosion, so that the stability of the reinforcement ring is considerably improved compared to other materials, such as a metal reinforcement ring. Since so In general, the protective layer is constructed as a sheet relatively thin, the material of the reinforcement ring that is built in one piece with the protective layer presents a greater material thickness to achieve the desired height of the reinforcement material. For construction on a piece of the ring Reinforcement and protective layer are especially suitable those chemically resistant materials that essentially do not have no or very small compressibility, to meet also with the mechanical requirements of the reinforcement ring. PTFE is For this the right material.

Under the present invention they must also count deviations of the reinforcement ring described above, in the which the reinforcement ring has, not in its entire circumference, less deformability or resistance greater than the ring base. It may be enough, and to save material, if distributed in several places peripherally in the reinforcement ring a material is provided that has a lower deformability than the base ring In another constructive alternative way, instead of a complete reinforcement ring can also be distributed elements loose not linked with each other that have less deformability than the base ring but have a height less than the base ring, like the reinforcement ring described above. These elements can be circle segments or also by for example, plates or discs of a solid material, fused with the elastic material of the base ring or joined with it. Is given by assuming that these elements fulfill the functions of the ring of reinforcement described above, in particular the limitation of the compression when installing the gasket.

The base ring of the chord ring with the invention presents a flat cross section that extends in the plane of the ring, that is, essentially, in the form of an annular disk With special preference, the cross section of the base ring has at least one bulge, which starting of the upper face and the lower face of the base ring which they have the flat cross section extends upwards and towards  below, that is, in the direction of the contact surfaces of the parts that are going to join one another tightly fluid. The bulge extends in the peripheral direction preferably throughout the periphery of the base ring, and in alternative configurations may be appropriate to provide in the section transverse base ring two or more bulges. Through one or more bulges on the sealing surface the compression further increases partially which improves the tightness especially in the case of gassing media or in the case of irregular sealing surfaces.

Other advantages, features and possibilities Construction will be clarified based on the following description of some forms of execution and the images that are accompany.

Figure 1 shows in cross section a flat seal ring according to the invention with reinforcement ring at the outer peripheral edge of the base ring.

Figure 2 shows in cross section a flat seal ring according to the invention with reinforcement ring at the inner peripheral edge of the base ring.

Figure 3 shows in cross section a flat gasket ring with a reinforcement ring that is not built in one piece with the protection layer material, in the outer peripheral edge of the base ring.

Figure 4 shows the application of the ring of flat gasket according to figure 3 to seal the transition of two pipe pieces

Figure 5 shows the application of the ring of flat joint in a flange joint.

Figure 6 shows the application of the ring flat gasket according to figure 3 to seal a valve in a installation.

Figure 7 shows the application of the ring flat gasket according to figure 3 to seal a valve in a head Dosing pump

Figures 1 and 2 show constructive forms of the flat seal ring 1 with a base ring 2 and a ring of 3 or 3 'reinforcement, where in the construction variant according to the figure 1 the reinforcement ring 3 extends along the edge outer peripheral of the base ring 2. In the construction variant according to figure 2 the reinforcement ring 3 'extends along the edge inner peripheral of the base ring 2. The base ring 2 of all  constructive forms according to figures 1, 2 and 3 consists of a deformable elastic material 6, which at least partially is wrapped by a protection layer 4. Protection layer 4 is properly formed by a PTFE sheet that protects the deformable elastic material 6 before an attack by a fluid chemically aggressive The base rings 2 of the seal rings planes 1 represented in figures 1, 2 and 3 each presents them a circumferential bulge 5 than in the section Transverse base ring are represented as elevations up and down the otherwise flat surfaces outside

In the flat seal ring according to the figure 1 the deformable elastic material 6 of the base ring 2 is fully wrapped by protection layer 4 and the layer of protection 4 protrudes from the outer periphery of the ring to the reinforcement ring 3. Reinforcement ring 3 may be manufactured hence the same material as the protective layer 4. The ring reinforcement 3 is located in axial direction centered with respect to the base ring 2 and has a height less than the axial direction of the base ring 2.

In the construction variant according to figure 2 the 3 'reinforcement ring extends through the inner peripheral edge of the base ring 2 and is constructed in one piece with the material of the protection layer 4, as well as the seal ring according to Figure 1. The protective layer 4 is provided on the face upper and lower face of base ring 2 and extends around the inner surface of the base ring 2. The edge outside of the base ring 2 is not covered by the layer of protection 4.

In the seal ring according to figure 3 the 3 '' reinforcement ring is provided on the peripheral edge outside of the base ring 2, however unlike the rings of joint planes according to the figures of the base ring 2.1 and 2 no It is built in one piece with the layer material of protection 4. On the flat seal ring according to figure 3 the 3 '' reinforcement ring is composed of a hard plastic or metal and it is embedded by closing form in the elastic material 6 deformable

Figure 4 shows the mounting of the ring flat gasket according to figure 3 between the connecting ends of two pipe pieces 7, being represented in figure 4 by dotted line the original basic non-pressed ring shape flat seal or base ring 2. It can be clearly recognized that in uncompressed state the base ring 2 with the bulge 5 in uncompressed state is clearly higher than in state compressed. In compressed state the base ring 2 takes exactly the same height as the reinforcement ring 3 'limiter of the compression.

Figures 5, 6 and 7 show examples for the Application of flat seal ring. According to figure 5, the ring flat gasket is used in a flange, consisting of two 8 and 8 'pipe pieces to be joined and bolted 9. Al fabricate the joint the pipe pieces 8 and 8 'move one towards the other by screwing the bolts in the direction of the two arrows represented and compress the flat seal ring exactly in axial direction

Figure 6 shows the application of the ring flat gasket according to figure 3 for the watertight joint fluids between a fluid connection piece 10 and a body 12 of valve by means of a threaded joint using nut 11. Also here the compression of the flat seal ring occurs in axial direction towards the ring, when the connecting part 10 of the fluid and the valve body 12 move towards each other by the tighten nut 11.

Figure 7 shows the use of the ring flat gasket for fluid tight connection of a head 13 of metering pump with a valve 14. Compression and movement of mutual approximation of the surfaces to be sealed between the head 13 of the metering pump and the valve 14 is produced here by screwing the valve 14 and with it by a movement rotating around the axis of the ring.

Claims (3)

1. Flat seal ring (1) for the manufacture of a fluid-tight joint of two surfaces that must be sealed by a clamping force against each other, where the ring (1) has a base ring (2) deformable elastic and at the inner peripheral edge and / or at the outer peripheral edge has a reinforcement ring (3, 3 ', 3''), where the reinforcement ring, at least perpendicular to the plane of the ring, has a less deformability or greater rigidity than the base ring (2) and where the height of the reinforcement ring vertically to the plane of the ring is less than the greater height of the base ring (2) perpendicular to the plane of the ring and where on the outer surface of the elastic base ring is provided, at least in sections, at least one protective layer 4 which is made of one piece with the reinforcement ring (3, 3 ', 3'') in PTFE or other material which in regards to its chemical stability against corrosion s It is similar to PTFE, characterized in that the reinforcement ring is firmly connected to the base ring by a projection or adhesive procedure. 2. Flat seal ring according to claim 1, characterized in that both a reinforcing ring (3, 3 ', 3'') is provided on both the outer peripheral edge and the inner peripheral edge of the base ring (2). 3. Flat seal ring according to one of claims 1 or 2, characterized in that the reinforcement ring or reinforcement rings (3, 3 ', 3'') is made of plastic or metal, preferably non-oxidizable metal, especially Preferred stainless steel.